This research program is concerned with certain genetic aspects of the membrane protein of erythrocytes and lymphocytes. Studies of red cell membranes have developed methods for solubilization, purification and partial extraction of the major membrane glycoproteins. The biochemical and immuno- chemical features of the minor erythrocyte glycoproteins were shown to differ from the major glycoprotein in man. Comparative studies of the membrane glycoproteins of various species were also performed. Red cells of persons with various inherited disorders associated with membrane function were examined. The surface immunoglobulin receptors of long-term cultured lymphoid cells were analyzed and the major immunoglobulin antigens determined as well as the quantitative relationship between heavy and light chains. Further studies have involved the interaction between Ig surface receptors beta2 microglobulin, and complement receptor sites.